Machine for covering wire with a helical wrapping



Jan. 25, 1938. A. J. SANDS 2,106,437

MACHINE FOR COVERING WIRE WITH A HELICAL WRAPPING Filed oct. 5, 193s HfM s l, amnuunnu: i?

Patented Jan. 25, 1938 UNITED STATES mme Foa oovEnING'wlaa Hamon.waArmNa WITH A Alexander John Sands, Westminster, London, England,assignor'to The London Electric Wire Company and Smiths Limited, London,England, a corporation ol Great Britain Application october-,5, 1936,serial No. 104,124 In Great Britain August 1s, loss 44 Claims.

This invention relates to machines for covering wire or the like with ahelical wrapping, more g particularly for electrical insulationpurposes.

The wrapping may be constituted by paper, cellulose cotton, wool orsilk, preferably in ribbon or tape form and the machine employed is onein which a wire to be wrapped is continuously drawn through the centreof a rotary head arranged to rotate about the axis of the wire andcarrying a disc-like roll, or similar convenient package of wrappingmaterial which is wrapped helically around the wire by the combinationof the axial movement of the wire and the rotary movement of the headwhich carries the wrapping material around the wire as it is unwoundfrom the roll carried by the head.

When covering wire with a wrapping material for electrical insulationpurposes, it is important that the tension in the wrapping materialshall be as uniform as possible through the entire wrapping operation.

In the majority of machines of this nature, the package of wrappingmaterial is carried on a rotatable sleeve, platform or similar suitablesupport which is capable of rotation independent of the head of themachine, and numerous proposals have been adopted for controlling thetension in the draw-olf of the wrapping material, by the application offriction. In one form of construction the friction has been applied tothe surface of a disc-like roll or similar convenient package of supplymaterial which is carried on a rotatable sleeve, platform or othersuitable support, such a construction however, being subject tocentrifugal loads, also in certain cases damage to the wrapping materialmay result; in another form of construction, the friction is applied tothe rotatable sleeve, platform or other suitable support which carriesthe disc-like roll or similar convenient package of wrapping material,but with such a construction, it is necessary for frequent addustment tobe made to compensate for the decrease in the diameter of the disc-likeroll or similar convenient package of wrapping material. In yet anotherform of construction, the friction has been applied to the sleeve andhas been controlled by the tension in the wrapping material. Such aconstruction however, is of necessity, very delicate and somewhatexpensive to manufacture.

The present invention aims at providing an improved, simple and efcientmeans whereby the tension in the supply material is maintainedsubstantially constant throughout the wrapping operation.

In a machine for providing wire with a helical wrapping, according tothe present invention, means by which tension of the wrapping materialis maintained substantially constant during an operation constituted bycontinuous substantial peripheral support of the package of wrapping 5material on the head.

Preferably, the machineL comprises a plate adapted to rotate about awire passing through its axis, the surface of which plate is so shapedor dished that an annular disc-like roll or similar l0 convenientpackage of wrapping material, for example, paper, which is carried onsaid surface is in contact with said surface only at its peripheral edgeat all periods during a wrapping operation.

'I'he disc-like roll or similar convenient package is preferably locatedon a central boss rising from the plate and formed integral therewith.

A device embodying the invention is herein after described and shownI inthe'accompanying drawingz- Y Figure 1 is a sectional elevation taken onthe lline I-I of Figure 2 with the roller guide member 9 shown in fullfor the sake of clarity, and

Figure 2 is a plan view.

The h d comprises a stationary sleeve bearing I, on w ch. the disc head`2 islmounted through a Journal race 3. The disc head 2 has a centralboss 4- which carries the journal races 3 and the driving pulley 3a anda central :boss la adapted to locate the package hereinafterparticularly referred to.

This spigot la, also carries a covering plate 6 of known type, arrangedwith usual means Il for pressing the wrapping tightly intol position on35 the wire. An adjustable guide member l for the wrapping material iscarried on the central boss 4a. i l

Around the central bossla, the head extends in disc formation 8 having aroller guide member 40 9 and a fixed inclined guide member l0 at pointson its circumference. A dished plate i I is secured to the disc 8 bymeans of bolts i2. A roll of paper strip I 3 rests on the dished plateIl at its periphery only and is maintained in lits correct position bymeans of the package locating rlng.

The operation of the head is as follows:-

The wire i5 passes from a suitable source of supply through thestationary sleeve bearing I and through the covering plate 6. The paperstrip from the roll I3, passes around the roller guide member 9, aroundthe fixed inclined guide member i0 and under the horizontal arm of theadjustable guide member 1, which guide member 'i ensures the correct layof the paper strip for its 30 more application to the wire I5. Finally,the paper passes around the wire Il, passing through the head in thedirection of the arrow A. After the strip has been applied to the wire,it passes through the device Il.

It is -preferred to use that material known as bakelized fabric for theYdished plate Il.

By mounting the disc-like roll or similarconvenient package of thesupply material on the dished plate Il, it will be seen that the speedof rotation of the package I3 will be greater or less than the speed ofrotation of the head, dependent upon the direction of such rotation inrelation to the direction of the unwinding of the package, and that thetension of the draw-off of the material will be dependent, to a largeextent, on the friction between the peripheral edge of the saiddisc-like roll or similar convenient package and the surface ofthedished plate Il.

It will be apparent that the external diameter of the package ofwrapping material will steadily decrease as the materialis applied tothe wire and that the turning moment for a given tension in the materialwill also decrease in direct proportion to the diameter, and suchdecrease will be compensated for, by the reduction in friction betweenthe peripheral edge of the package and the surface of the dished plate,which friction will decrease approximately in proportion to the weight,i. e., in proportion to the rediction in face area of the. package,whilst the braking effect of the friction between the centre ofthepackage and the locating boss will tend to increase in direct proportionto the speed of rotation of the package in relation to the dished plate,with the result, that the tension in the draw-.off of material willremain substantially constant.

The co-eiflcient of friction between the surface of the dished plate andthe peripheral edge of the disc-like roll or similar convenient packagemay be modified by the selection of various materials for the surface ofthe dished plate and/or by preparation of such surface in various ways.

The degree of tension in the material may be further controlled by therelative dimensions of the package, the preferred annular disc formconsisting of a single width of the material wound in a continuousspiral or convolute formation being modified by traversing the materialduring winding to produce a package of discform, but having a thicknessgreater than the single width of the material. It will be readilyapparent, that such a modified package will result in an increase of thetension in the material during the wrapping operation according to theincrease in the width of the package.

What is claimed is;- 1. In a machine for providing wire with a helicalwrapping, a disc-like head, said disc-like head beingarranged torotate/about a wire which passes vertically through the axis of saidhead,

an annular package of wrapping material intape-like convolute formsupported on said disclike head having an effective contact with saidhead at the periphery of said package only, so that the tension in thewrapping material is maintained constant by the weight of thewrappingmaterial on the surface at all periods during a wrapping operation.

2. In a machine for providing wire with a helical wrapping, a disc-likehead, said disc-like head being arranged to rotate about a wire whichpasses vertically through the axis of said head, a central boss, saidboss rising from the centre of said head and rotating therewith, anannular package of wrapping material in tape-like convolute formsupported on said disc-like head and` held in position thereon by saidcentral boss,4 a

dished surface to said disc-like head, said annular package beingsupported only at its periphery on said dished surface so that thetension in the wrapping material is maintained constant by the weightonly of the wrapping material on the dished surface at all periodsduring a wrapping operation.

3. In a machine for providing Wire with a helical wrapping, a relativelyflat disc-like head, said disc-Alike head being arranged to rotate abouta wire which 'passes vertically through the axis of said head, said headhaving a dished upper surface, an annularpackage of wrapping material intape-like convolute form supported on said dished surface of saiddisc-like head, said annular package being supported only at itsperiphery on said dished surface so that the tension in the wrappingmaterial is maintained constant by the weight onlyof the wrappingmaterial on the dished surface at all periods during a wrappingoperation.

4. In a machine for providing wire with a helical wrapping, a disc-likehead, said disc-like head being arranged to rotate about a Wire whichpasses vertically through the axis of said head, a central boss, saidboss rising from the centre of said head and formed integral therewith,a flat surface to .said disc-like head, a dished surface located on saidfiat surface of said disc-like head, an annular package of wrappingmaterial in tape-like convolute form supported on said dished surfaceand held in position thereon by said central boss, said annular packagebeing supported only at its peripheryon said dished surface, so that thetension in the Wrapping material is maintained constant by the weightofthe Wrapping material on the dished surface at all periods 4during awrapping operation.

